Flexible sanding disc unit

ABSTRACT

A flexible adapter unit is used in mounting a flexible abrasive disc to the surface of a motorized rotary operator such as is commonly used in relatively light sanding operations. As sold, the unit is a package-like lamination of three discs adhesively secured in a stack, namely a basic intermediate membrane disc bearing a pressure-sensitive coating on each of the opposite sides thereof, and a pair of thin outer strippable protective cover members, one adhered releasably on either side of the membrane. Said last-named members are thin flexible discs, each preferably being wax or otherwise coated on an inner side thereof to present a somewhat glossy, entirely non-tacky surface adherently engaging a membrane surface coating. The intermediate membrane disc is also flexible, and may vary considerably as to material; and it is coated on its opposite sides with pressuresensitive adhesive layers. These, though by preference being in common of a known latex composition, yet vary considerably in an operational characteristic of said composition. That is, one of said coatings or layers, as applied in use to a rotary tool surface, is a relatively heavy one having a relatively high degree of tacky adhesiveness, so as to adhere tightly to the tool surface as so applied, yet being removably strippable manually from said surface. The other or outer adhesive layer is lighter and substantially less tacky adhesively, yet sufficiently so to have ready pressed-on engagement with the non-abrasive rear side of a sanding disc, while still allowing the latter to be readily stripped from the membrane disc and discarded when worn.

United States Patent [1 1 Clemente l l FLEXIBLE SANDING DISC UNIT JosephV. Clemente. 1221 Fairholme. Grosse Pointe Woods, Mich. 48236 [22]Filed: Dec. 26, 1973 [21] Appl. No.: 427,849

[76] Inventor:

Primary E.\'aminerlames L. Jones, Jr. Attorney. Agent. orFirmWhittemorc. Hulbert & Belknap [57] ABSTRACT A flexible adapter unitis used in mounting a flexible abrasive disc to the surface of amotorized rotary operator such as is commonly used in relatively lightsanding operations. As sold. the unit is a package-like Apr. 8, 1975lamination of three discs adhesively secured in a stack. namely a basicintermediate membrane disc bearing a pressure-sensitive coating on eachof the opposite sides thereof. and a pair of thin outer strippableprotective cover members, one adhered relcasably on either side of themembrane. Said last-named members are thin flexible discs. eachpreferably being wax or otherwise coated on an inner side thereof topresent a somewhat glossy. entirely non-tacky surface adherentlyengaging a membrane surface coating. The intermediate membrane disc isalso flexible. and may vary considerably as to material; and it iscoated on its opposite sides with pressure-sensitive adhesive layers.These. though by preference being in common of a known latexcomposition, yet vary considerably in an operational characteristic ofsaid composition. That is. one of said coatings or layers, as applied inuse to a rotary tool surface, is a relatively heavy one having arelatively high degree of tacky adhesiveness. so as to adhere tightly tothe tool surface as so applied. yet being removably strippable manuallyfrom said surface. The other or outer adhesive layer is lighter andsubstantially less tacky adhesively. yet sufficiently so to have readypressed-on engagement with the nonabrasive rear side of a sanding disc.while still allowing the latter to be readily stripped from the membranedisc and discarded when worn.

10 Claims. 4 Drawing Figures I FLEXIBLE SANDING DISC UNIT BACKGROUND OFTHE INVENTION 1. Field of the Invention The sanding adapter lends itselfto any application heretofore open to the use of removable or removablystrippable sanding or like abrasive members, in particular in rotarydisc sanders usually employed manually.

2. Description of the Prior Art In the past, in applications generallysimilar to that of the present invention, a sandpaper sheet, disc orlike flexible abrasive unit has been removably mounted on the surface ofa compressible cushioned rotor pad, or equivalent backing member, bysimply applying fluid adhesive to the face of the pad and pressing asandpaper sheet, disc or the like onto the adhesive-coated surface. Inapplications in which the backing surface is afforded directly by aninflexible disc, this has in the past been coated with an appropriatemastic composition softened under frictional heat, with the abrasivedisc pressed thereto before it takes a set. Said conventional proceduresare fairly inexpensive material-wise, but over the long run ofreplacements of worn abrasive sheets are inconvenient and time-wasting.

According to an earlier improvement on the procedure first describedabove, sandpaper discs have been sold with a pre-applied pressuresensitive adhesive on the non-abrasive side, that coating beingprotected prior to sale and use by an appropriate slip or strip sheetcover, to be peeled away and discarded before pressure-applying thesandpaper disc against a cushioning pad or other abrasive-mountingsurface of the tool. This improvement is, of course, more expensive thanthe case of a plain sandpaper disc, the number of replacement piecesbeing assumedly the same in each instance.

SUMMARY OF THE INVENTION The invention is a substantial improvement overboth of the above prior art concepts in its use ofa single flexiblemembrane which in operation is interposed between a tool pad, cushion orequivalent backing surface and a sandpaper or other flexible abrasivedisc as mounted on said surface by the membrane. The invention inparticular distinguishes over and improves on prior expedients in thatthe special membrane is protected prior to sale and/or use between apair of like thin external strip discs or sheets. These serve asprotective covers in the handling of the unit, said discs preferablyhaving an inner nontaeky slip coat of clear wax-like or varnish-likematerial. This facilitates their stripping by peeling from the surfacesof the basic intermediate membrane, the latter as distinctively coatedpressure-sensitively in the manner described in the Abstractv The padcomponent of the compressively mounted combination may be permanentlysupported on a relatively rigid backing plate of metal or plastic, thepad comprising a vinyl or leather-like facing to which the membrane isadherently mounted, and a vinyl foam cushion part between said facingand the backing plate. The cushion is secured relatively permanently tothe plate and the facing is secured equally permanently to the foam, asby a pressure bonded or contact cement. Said vinyl facing preferablycarries a slip coat of varnish or varnish-like material to enable it tostick moder ately strongly to the membranes inner, heavier strengthpressure-sensitive adhesive without, however, any likelihood of themembrane being dislodged from the backing pad under severe sanding.

The membrane may be of any appropriate grade of fiberboard or heavypaper material, but of whatever stock the membrane may be comprised, itshould not tear readily, particularly in active abrading use; and withthis in mind the membrane may also be of a tex tured fabric or wovencloth.

The ability in accordance with the invention to use plain unfaced andunprocessed sandpaper discs of course eliminates the cost factor inpre-coating each disc with a pressure-sensitive adhesive; a singlecoating of the inner tool-engaging surface of the membrane of theinvention eliminates all of these costs. Likewise, a single coating ofthe external sanding disc-mounting surface of the membrane is all thatis required in the successive use of a multiplicity of sandpaper discsof like or different grades, prior to their discard and replacement asthey become worn and useless. The worn disc is simply stripped or peeledoff the membrane, which remains in place on the tool pad or othermounting part with both of its pressure-sensitive coatings intact.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an end face elevation of apackage-type lamination of special membrane and protective covercomponents, the form in which the adapter unit is sold and handled priorto use, the view illustrating in a partially fanned arrangement innerand outer protective strip discs and the intermediate membrane disc ofthe combination, the latter as coated pressure-sensitively on itsopposite side surfaces;

FIG. 2 is a view in transverse diametral section through the laminationof FIG. I, being in an enlarged scale schematically distorted somewhatfor clarity in thicknesses of constituent disc and coating components',

FIG. 3 is a substantially full scale perspective view of the laminatedpackage unit of FIGS. 1 and 2 as stripped of its protective covers andapplied to a sander disc base pad structure, being equipped with asanding disc and with the latter and its supporting membrane shownpartially peeled away from a supporting base pad, and

FIG. 4 is a side-elevational view, partially broken away, showing atypical application of the unit as back ing pad-mounted for use on aconventional motorized hand sander.

DESCRIPTION OF A PREFERRED EMBODIMENT FIGS. 1 and 2 somewhatschematically show, and not in necessarily scaled relation of theirparts, the adapter unit of the invention, generally designated by thereference numeral 10, in the package form in which it is merchandised,whether in an appropriate outer promotional envelope or not. This unitconsists of the essentially important membrane sheet or disc 12, whichmay be option ally constituted by a ruggedly strong flexible paper inany desired thickness, or may be constituted of a flexible grade ofpaperboard, fiberboard, a woven fabric, or like substantially inelasticthin sheet material. The material of membrane 12 is susceptible ofrelatively wide choice, so long as it has adequate strength and/ortoughness to resist the torsional stress to which it is subjected inuse, without tearing free from a support pad or disc on the sandingtool.

As thus constituted, an inner or rear surface of membrane disc 12 isrelatively heavily coated with a pressure-sensitive adhesive of therubber latex type, such as is readily available on the market indifferent grades. This rear or inner coating of membrane 12 is indicatedat 13, and it is selected and set to afford a relatively high degree ofadhesive strength or tackiness when pressure-sensitive applied against anon-coated surface. The opposite outer or front surface of membrane disc12 is, on the other hand. provided with a coating 14 of the same generallatex type, but in a thickness and/or grade such as to present when seta substantially lesser degree of adhesive strength or tackiness thandoes the inner or rear coating 13.

Finally, the membrane is removably and adherently faced at itsrespective coatings l3 and 14 with relatively thin protective strip orcover sheets 15, 16. These are in the form of light gauge paper discswhich are treated only on their membrane-facing surfaces, as by anappropriate dried waxy or varnish-like application, to render themindividually non-tacky, but still readily strippable by the fingers fromthe respective coated membrane surfaces of unit 10. When the discs l5,16 are stripped from the membrane 12, the latter is applied removablyand adherently as a part of a backing pad and abrasive disc laminationunit or combination. This combination, generally designated in FIGS. 3and 4 by the reference numeral 17, presents a further novel and improvedaspect of the invention,

Said laminated unit 17 comprises a more or less conventionalsub-combination ofa relatively rigid circular backing plate 18 of metalor plastic material equipped at a central cavity thereof with acylindrical washer-like reinforcement 19 which presents a preferablyintegral rearwardly extending and exposed stem 20 at which the adaptedsander disc unit 17 is chucked to an entirely conventional motorizedsander 22. There is typically an eccentric mount of said unit to thehead 23 of sander 22, so that the unit 17 has an orbital sanding action,as indicated by the double-headed arrow in FIG. 4. in some cases, thestem will be threaded, as at 20' (FIG. 4), for its removable mount tothe tool 22. Of course, the operational nature of said tool is entirelyoptional; but a dual action air motor driven one typically appears inFIG. 4.

FIG. 3 shows the rigid backing plate 18 of unit 17 as having arelatively permanent bond at a forward interface surface 25 thereof witha vinyl foam cushion 26 of cylindrical form and substantial thickness;and the forward surface of this cushion is faced by a leather-like vinylsheet 27 having relatively great strength in tension and torsion. Bypreference, the vinyl facing 27 is forwardly provided with a slip coatof a clear varnish or varnish-like material for an improved adherencethereto of membrane disc 12.

That disc is shown in FIG. 3 as having its high strength or tacky innerlatex coating 13 removably adhered to the cushion pad facing 27, withits more lightly adherent coating 14, as stripped of the protectivecover 16, exposed and adherently engaged by the plain rear surface of aconventional sanding disc 28.

As thus constituted, the backed membrane and pad unit is resistant totear and to dislodgement from its pad component under relatively heavyduty sanding operation. Yet the relatively small degree of tackiness offorward surface [4 enables the sanding disc 28 to be marginally liftedfrom membrane coating 14 and peeled off the latter for replacement whenworn with another abrasive disc; and the greater tackiness of rearmembrane coating 13 is sufficient to resist its separation from cushionpad 26 in said replacement removal of the sanding disc, while at thesame time enabling the membrane 12 itself to be similarly stripped alongwith the sandpaper from the facing 27 of the rotary tool mount.

What is claimed is:

l. A flexible adapter unit for mounting an abrasive sheet on a surfaceof an operator for said sheet, said unit consisting in its entirety of atemporary lamination of an intermediate flexible membrane of thin,substantially inelastic sheet material and a pair of flexible protectivestrip sheets having temporarily-adhered application respectively toinner and outer surfaces of said membrane, said application beingthrough the agency of a pressure-sensitive adhesive coating pre-appliedon the inner membrane surface, which coating when exposed andpressure-applied on said operator surface has a relatively strong butreleasable bond to that surface, and another and specifically differentpressuresensitive adhesive coating pre-applied on the outer membranesurface, which lastnamed coating when exposed and pressure'applied tothe abrasive sheet has a readily releaseable bond to said abrasivesheet, the respective protective strip sheets being relatively readilypeeled from said respective membrane coatings, the adhesive bond to saidabrasive sheet effected by said first-named coating on the outermembrane surface being substantially less strong and more readilyreleasable than the bond ofthe inner membrane surface coating to saidoperator surface.

2. The adapter unit of claim 1, in which the membrane bonds to therespective strip sheets are weaker than either of the abrasive sheet andoperator surface bonds.

3. The adapter unit of claim 1 as a circular disc unit applied inadhesive combination with a motor-driven operator presenting saidfirst-named surface, with a protective sheet of the unit stripped fromthe inner membrane surface and that surface adhered to said first-namedoperator surface.

4. The adapter unit of claim 2 as a circular disc unit applied inadhesive combination with a motor-driven operator presenting saidfirst-named surface, with a protective sheet of the unit stripped fromthe inner membrane surface and that surface adhered to said first-namedoperator surface.

5. The combination of a unit in accordance with claim 1 as stripped ofone of said protective sheets to expose said inner coated membranesurface, and a backing member to which said membrane is adherentlysecured at said inner surface thereofv 6. The combination of a unit inaccordance with claim 1 as stripped of both of said protective sheets toexpose said inner and outer coated membrane surfaces, a backing memberto which said membrane is adherently secured at said inner surfacethereof, and an abrasive sheet releasably secured adherently to saidouter coated surface of said membrane.

7. The combination of claim 5, in which said backing member is ayieldably faced one, at the facing of which said inner membrane coatinghas a relatively strong but releasable bond.

8. The combination of claim 6, in which said backing member is ayieldably faced one, at the facing of which said inner membrane coatinghas a relatively strong but releasable bond.

9. The combination of a flexible adapter unit for mounting an abrasivesheet on a surface of an operator for said sheet, said unit comprising atemporary lamination of an intermediate flexible membrane and a pair offlexible protective strip sheets having temporarilyadhered applicationrespectively to inner and outer surfaces of said membrane, saidapplication being through the agency of a pressure-sensitive adhesivecoating preapplied on the inner membrane surface, which coating whenexposed and pressure-applied on said operator surface has a relativelystrong but releasable bond to that surface, another pressure-sensitiveadhesive coating pre-applied on the outer membrane surface, whichlast-named coating when exposed and pressure-applied to the abrasivesheet has a releasable bond to said abrasive sheet, the respectiveprotective strip sheets being relatively readily peeled from saidrespective mem brane coatings, said unit being adapted to be stripped ofone of said protective sheets to expose said inner coated membranesurface, a backing member to which said membrane is adherently securedat said inner surface thereof, said backing member being a yieldablyfaced one, at the facing of which said inner membrane coating has arelatively strong but releasable bond, the yieldable facing of saidbacking member comprising a foamed layer having a flexible facing sheetpermanently secured on an outer surface, and a relatively rigid supportmember to which an inner surface of said foamed layer is relativelypermanently secured.

10. The combination of a flexible adapter unit for mounting an abrasivesheet on a surface of an operator for said sheet, said unit comprising atemporary lamination of an intermediate flexible membrane and a pair offlexible protective strip sheets having temporarilyadhered applicationrespectively to inner and outer surfaces of said membrane, saidapplication being through the agency of a pressure-sensitive adhesivecoating preapplied on the inner membrane surface, which coating whenexposed and pressure-applied on said operator surface has a relativelystrong but releasable bond to that surface, another pressure-sensitiveadhesive coating pre-applied on the outer membrane surface, whichlast-named coating when exposed and pressure-applied to the abrasivesheet has a releasable bond to said abrasive sheet, the respectiveprotective strip sheets being relatively readily peeled from saidrespective membrane coatings, said unit being adapted to be stripped ofboth of said protective sheets to expose said inner and outer coatedmembrane surfaces, a backing member to which said membrane is adherentlysecured at said inner surface thereof, an abrasive sheet releasablysecured adherently to said outer coated surface of said membrane, saidbacking member being a yieldably faced one, at the facing of which saidinner membrane coating has a relatively strong but releasable bond, theyieldable facing of said backing member comprising a foamed layer havinga flexible facing sheet permanently secured on an outer surface, and arelatively rigid support member to which an inner surface of said foamedlayer is relatively permanently secured.

1. A flexible adapter unit for mounting an abrasive sheet on a surfaceof an operator for said sheet, said unit consisting in its entirety of atemporary lamination of an intermediate flexible membrane of thin,substantially inelastic sheet material and a pair of flexible protectivestrip sheets having temporarily-adhered application respectively toinner and outer surfaces of said membrane, said application beingthrough the agency of a pressure-sensitive adhesive coating pre-appliedon the inner membrane surface, which coating when exposed andpressure-applied on said operator surface has a relatively strong butreleasable bond to that surface, and another and specifically differentpressure-sensitive adhesive coating pre-applied on the outer membranesurface, which last-named coating when exposed and pressure-applied tothe abrasive sheet has a readily releaseable bond to said abrasivesheet, the respective protective strip sheets being relatively readilypeeled from said respective membrane coatings, the adhesive bond to saidabrasive sheet effected by said first-named coating on the outermembrane surface being substantially less strong and more readilyreleasable than the bond of the inner membrane surface coating to saidoperator surface.
 2. The adapter unit of claim 1, in which the membranebonds to the respective strip sheets are weaker than either of theabrasive sheet and operator surface bonds.
 3. The adapter unit of claim1 as a circular disc unit applied in adhesive combination with amotor-driven operator presenting said first-named surface, with aprotective sheet of the unit stripped from the inner membrane surfaceand that surface adhered to said first-named operator surface.
 4. Theadapter unit of claim 2 as a circular disc unit applied in adhesivecombination with a motor-driven operator presenting said first-namedsurface, with a protective sheet of the unit stripped from the innermembrane surface and that surface adhered to said first-named operatorsurface.
 5. The combination of a unit in accordance with claim 1 asstripped of one of said protective sheets to expose said inner coatedmembrane surface, and a backing member to which said membrane isadherently secured at said inner surface thereof.
 6. The combination ofa unit in accordance with claim 1 as stripped of both of said protectivesheets to expose said inner and outer coated membrane surfaces, abacking member to which said membrane is adherently secured at saidinner surface thereof, and an abrasive sheet releasably securedadherently to said outer coated surface of said membrane.
 7. Thecombination of claim 5, in which said backing member is a yieldablyfaced one, at the facing of which said inner membrane coating has arelatively strong but releasable bond.
 8. The combination of claim 6, inwhich said backing member is a yieldably faced one, at the facing ofwhich said inner membrane coating has a relatively strong but releasablebond.
 9. The combination of a flexible adapter unit for mounting anabrasive sheet on a surface of an operator for said sheet, said unitcomprising a temporary lamination of an intermediate flexible membraneand a pair of flexible protective strip sheets havingtemporarily-adhered application respectively to inner and outer surfacesof said membrane, said application being through the agency of apressure-sensitive adhesive coating pre-applied on the inner membranesurface, which coating when exposed and pressure-applied on saidoperator surface has a relatively strong but releasable bond to thatsurface, another pressure-sensitive adhesive coating pre-applied on theouter membrane surface, which last-named coating when exposed andpressure-applied to the abrasive sheet has a releasable bond to saidabrasive sheet, the respective protective strip sheets being relativelyreadily peeled from said respective membrane coatings, said unit beingadapted to be stripped of one of said protective sheets to expose saidinner coated membrane surface, a backing member to which said membraneis adherently secured at said inner surface thereof, said backing memberbeing a yieldably faced one, at the facing of which said inner membranecoating has a relatively strong but releasable bond, the yieldablefacing of said backing member comprising a foamed layer having aflexible facing sheet permanently secured on an outer surface, and arelatively rigid support member to which an inner surface of said foamedlayer is relatively permanently secured.
 10. The combination of aflexible adapter unit for mounting an abrasive sheet on a surface of anoperator for said sheet, said unit comprising a temporary lamination ofan intermediate flexible membrane and a pair of flexible protectivestrip sheets having temporarily-adhered application respectively toinner and outer surfaces of said membrane, said application beingthrough the agency of a pressure-sensitive adhesive coating pre-appliedon the inner membrane surface, which coating when exposed andpressure-applied on said operator surface has a relatively strong butreleasable bond to that surface, another pressure-sensitive adhesivecoating pre-applied on the outer membrane surface, which last-namedcoating when exposed and pressure-applied to the abrasive sheet has areleasable bond to said abrasive sheet, the respective protective stripsheets being relatively readily peeled from said respective membranecoatings, said unit being adapted to be stripped of both of saidprotective sheets to expose said inner and outer coated membranesurfaces, a backing member to which said membrane is adherently securedat said inner surface thereof, an abrasive sheet releasably securedadherently to said outer coated surface of said membrane, said backingmember being a yieldably faced one, at the facing of which said innermembrane coating has a relatively strong but releasable bond, theyieldable facing of said backing member comprising a foamed layer havinga flexible facing sheet permanently secured on an outer surface, and arelatively rigid support member to which an inner surface of said foamedlayer is relatively permanently secured.